Ophthalmic lens



Feb. 5, 1935. A, LAABS 1,990,126

OPHTHALMIC LENS Original Filed Dec. 27, 1927 INVENTOR m (1 baabs. W WR Y Pa a]... 5.193 A 1,990,126

UNITED A E "PATENT oFFIcE OPHTHALMIC LENS Max A. Laabs, Southbridge, Mass., assignor to American Optical Company, Southbridge, Mass., a voluntary association of Massachusetts Original applications December 27, 1927, Serial No. 242,637, and December- 12, 1930, Serial No.

. 501,879. Divided and this application June 20, 1932, Serial No. 618,194

3 Claims. (01; 88-54) This invention relates to an improved multimajor blank thus making two fusing operations focal or bifocal lens and has particular 'refnecessary. I I I erence to a fused multifocal or bifocal lens. Another method was to grind a circular coun- This application is a division of my applicatersink in the major blank as before and to fuse I 5 tion for United States Letters Patent filed'in the a circular segment of different index of re-frac 5 United States Patent Office December 2'7, 192'? tioninto the ground countersink, then to-split and given the Serial Number 242,637 and which the inajorb e through e C r Of he 00111 has become patent serial No. 1,871,123, dated tersink and then fuse along the split j edge August 9, 1932 and of my application for Letanother piece of glass of the same index of re-' I ters Patent filed December 12, 1930, Serial Numfraction as the major blank. This also involved 10 her 501,879, and is directed to the product ittwo fusing steps, first fusing the segment into self,- namely a novel multifocal or bifocal lens the countersink and then fusing a separatepiece and/or lens blank. of glass along the split edge. The fusing opera- The principal objectof the invention is toproti is V y eXDeHSiVe probably e most vide a multifocal or bifocal lens or a blank for expensive step in the production of fused multi- 15 the same with a fused segmental portion having focal" lenses. There are certain chemical reacan irregular outline shape, that is to say an tions which take place in the s ng and Where outline a portion of which departs from a full a double fusing is necessary the optical propercircle, whereby portions of the outline have difties of the finished'produot are likely to be deferent radiiof curvature or one portion of the t y i. i I 2 outline intersects anotherportion instead of be- I therefore, one O the 'p e p Objeets 0f I ing tangential thereto. I I my invention to'avoid this double fusing and to.

Another object of the invention is to provide makea fused multifocal lens so that thc e II improved means for shaping and/or surfacing ent mayfi' e ed in major blank with thefusing surfaces of such multifocal or bifocal 0116 Ope ation only. I I, lenses having segments of irregular outline.- "The 'olilil ne'fih p D e S b 'ha-S' been Other objects and advantages of the invention circular, 'It' has b n und Segments n will become apparent from' the following 19- circular'inoutline butof variousodcl shap'es,'such I scription taken in connection with the accom-, a embedying th eomhihetiehs ra h and panying drawing and it will be apparent that 'curved'lines, all straight lines or a combination many changes in the steps of the process and the Of Cu ves Of d ferent radii p ss adva ta es arrangement and details of construction of the not Present in e a f i t' aSIbee i parts maybe made without departing from the difficult and expensive if not 'impracticable to spirit of theIinvention as set forth in the accomp 0du e h d pe Segments and b u panying claims. I, therefore, do not wish td be larir'th s s f r su h seg nts. It is therelimited to the exact arrangements shown and e a One: Of the p n p Objects 0f v y'i described, the preferred forms only having been vention to provid SimlJ1e;efiiCieI1t a s shown by way of illustration. calmeansof producing such odd shape-segments There has been a marked effort in the art and the recesses therefor. 40 recently to perfect a so-called monaxial or mono- Referring to the drawing:

centric multifocal or bifocal ophthalmic lens F g. 1 8a p p f p V w a uffanwherein a small segment of glass of one index ing apparatus showing the method of grinding of refraction is fused into 'a. larger section of the countersinks in the major blanks; I glass ofdifferent index of refraction. There have Fig. 2 is a partialsection on line 22'of; Fig.1: been'two distinct methods of obtaining this re- Fig. Sis a partial sectional elevation ofa sursult. One of these methods comprised grinding acing apparatus Similar to F g. l" but showing a circular countersink in the major blank and a modification thereo t making a circular segment to fit in this 'counter- Fig. 4 is'a top view of Fig. 3; sink, the said segment being split through its Fig; 5 is a front view of a multifocal lens blank center, the upper half being of glass of the same showing the countersink portion surfaced as inindex of refraction as the major blank and the dicated in Fig. 1; I I lower half being of different index of refraction 1 Fig. 6 1s a-front view of a multifocal lens blank from the 'major blank. These two halves were showing one form of recess therein as surfaced first fused togetherand then the fused-segment on theapparatus of Fig. 4; I I or buttonwas again fusedi-nto' the recess in the F g. 7 is a view similar to Fig- 6' Showing 2H1v other shape of the recessed countersink as made on the apparatus'of Fig. 1;

Fig. 8 is a view similar to Fig. 7 showing an- ,other'outline shape of countersink as made on countersink formed on the opposite side of the lens.

erence characters denote" corresponding parts throughout, the principal objectv of the invention is tomake in one face of a major lens blank" 1 a recess or countersink 2 having the outline shapes indicated in Figs. 5, 6, 7 and 8 as well as other shapes. It will be understood that the under surface 3 of the countersink 2 is a regular shaped lens surface, preferably spherical in formation, which is preferably ground and polished to the required surface conformation. It. will be understood also that the angle at which this surface 3 is placed to the face surface 4 of the lens is important as bearing on the amount of displacement in passing from the upper or distance held 5 to the segment or reading field 6. In monaxial or monocentric multifocallenses this angularrelationship is such that there is no displacement of image in passing from the faced by guiding means to give the shape re-' distance field 5 to the reading fieldfi and it is one of the important features of my apparatus and process to provide means of making the surface 2 so related to the distance field 5 that if desired I can produce monaxial or, monocentric multifocal lenses requiring only one fusing. It will be understood that the segment or reading portion 6 is fused into the countersink or recess 2 or otherwise secured therein.

It will be notedthat the shape of the segment 2 in Fig. 5 has an upcurve top and a downcurve lower portion; while that shown in Fig. 6 has 'a straight top and a down curved lower portion.

The recess shown in Fig. 7 has a down-curve top and a down-curve bottom, while that shown in Fig. 8 has the top and bottom both straight.

Itwill be seen, therefore, the countersink portion 2 of various shapes can be formed and surquired. One method of producing the recesses 2 shown in Figs. 5,6, 7 and 8 is indicated in 1. This apparatus comprises a support 27 in which is mounted thelens holder support 28 carrying the lensholder 29. The lens blank 12 is mounted on the lens holder 29 andon top of the lens blank 12 is placed a guide member 30 having an edge shape 31 of the desired conformation. The frame 27 also carries a double cam curve. guide member 32 which has one cam curve conformation to which the under surface 3 of the countersink is to be' finished. and another to which the top shape of the countersink is tobe finished. Travellingon'the guide cam member 32 is theslide 33 carrying the tool spindle 34 which is rotated by thepulley 35 and beltf36. Mounted on the spindle 34 is the sur-' facing tool. 37 having a surfacing face of the curvature to which is desired to surfacethe under surface 3 of the countersink. The slide 33 is moved back and forth on the guide way 32 by the link 38 pivotally secured at 39 to the eccentric 40, which eccentric 40 is rotated by the pulley 41 and the belt 42. Theoperationof this device is as follows: The'guide member '30 having the desired shape edge 31 is arranged in place over the lens blank 12. The tool 37 is ro- Referring to the drawing whereinsimilar ref the spring 26.

forth along the edge 31 of the guide member 30 by means of the cam guide 32 and the eccentric 40 and its attachments. In this way contours may be ground of the shape shown in Figs.

5, 6, 7 and 8." In'all instances on curve of the cam guide 32 and the edge -31 must be the same. The guide plate 30 may be done away with if desired as the same result will be obtained by the-double cam guide 32, the plate 30 being used only as an extra guide for the tool on the lens.

'After the countersink 2 of desired outline shape and of desired surface formation has been formed in the major blank 1 a segment 6 is fashioned to fit therein and is thereafterwards fused or otherwise secured in place. After the segment 6 has been fused in placethe surface 4 is placed on the blank. This surface is continuous over the major portion5 as well as over the segment 6 and the proper angular relationship of the recess of countersinkZ to the surface 4 may be determined at the time the surface 4 is placed on the blank, the height and the width of the reading portion determining the relationship, whether monaxial with the major portion or eccentric thereto. Afterthe surface 4 hasbeen placedon the fused 'blank the prescription curve .43 may be ground Referring to Fig. 1, it will be, understood that one curvature of the guide cam 32 is the same as :the surfacing curvature of the tool 37 and the other curvature thereof the same as the edge shape 31 of the guide plate 30.. r

Where-it is desired to fashion the countersink 2 with a straight line at the top as shown in Fig. 6; one of the camcurves on the' guide 32 and the] edge 31 on the .plate'30 may be; made straight,

or an apparatus such as shown in'Fig. 3 may be used. This comprises asbefore the tool 7.hav-.

ing a spherical grinding. surface 8 mountedon the spindle 9 rotated bythe pulleylOand belt 11. 1 The lens blank 12 is mounted on the lens holder l3which is pivoted at-21 to a link 22 which is again pivoted at 23 to a slide 24 resiliently mounted in a slide support .25; and backed by The operation of this device isv as follows: The holder 13 is locked at 21 to. the desired angle and the blank 12 maybe movedto conform to the surface8 of the tool aboutthe pivot 23. The tool-7 is rotated with the lens blank 12 in contact therewithas shown in Fig. 4.

The operator presses the blank 12 down against the spring pressure 26 with his hand and moves the holder 13 along the slide 24, at the same time rocking it about the pivot 23. This produces the shape of countersink or recess shownin Fig. 6, that is, one having a straight top and a down.- wardly curved lower portion. I i s I,

To produce a lens such as shown in Fig. 5the slide 24 maybe curved asindicated by the line 44 in Fig". 4 and to-produce the lens shown in Fig. 7 the slide24 may be curved as indicated by the line 45in Fig. 4. To produce the'lens shown in Fig. 8 a tool such as 37 is used having a diam-,- eter equal to the distance between the top and bottom of the countersink 2. 1 This lens may be made by an apparatus such as shown in Fig. 1..

The outlines of" the segments and recesses for them may be made in other ways, such as moulding them to approximate shape and size and fin- It will be seen ishing as described above or they may be moulded or pressed while in plastic condition from heat to the desired outline.

From the foregoing it will be seen that I can make on the major blank of a multifocal lens a countersink or recess surface of desired surface conformation and desired contour shape whereby I may make a multifocal lens having its segment either in monaxial relationship to the major section or in eccentric relation thereto as desired.

Having described my invention I claim: 1. A multifocal or bifocal lens comprising a major portion of lens medium of one index of refraction having a seat thereon, said seat being located in the lower portion of said major. portion and being spaced from its contour edges, the sides and bottom edges of said seat being a continuous line of revolution and the top thereof being a transverse curved edge of a radius greater than the radius of the continuous line of revolution and intersecting said line at the sides of the seat and being concaved downwardly with respect to the horizontal meridian of the lens, and a minor portion of glassof different index of refraction secured to said seat and conforming in outline thereto, the top edge of said minor portion having substantial thickness and the side and bottom edges thereof having substantially no thickness, the said top edge being located adjacent to and throughout the major portion of its length below the center of the major portion the concavity of the said top edge being such as to provide a wide entrant field of vision when the eye passes from one focal field into the other.

2. A multifocal or bifocal lens comprising a major portion of lens medium of one index of refraction having a seat thereon, said seat being spaced from the contour edges of the major portion, the sides and bottom edges of said seat being a continuous line of revolution formed by the intersection of two differently generated curves on one face of the major portion and the top thereof being a transverse cliff type edge having a curved surface which is concaved downwardly with respect to the horizontal meridian having substantially no thickness, the said top edge being located adjacent to and throughout the major portion of its length below the center of the major portion, the concavity of the top 3 edge being such as to provide a wide entrant field of vision when the eye passes from one focal field into the other. e

3. A multifocal or bifocal lens comprising a major portion of lens medium of one index of refraction having a seat thereon,'said seat being spaced from the contour edges of said major portion, the sides and bottom edges of said seat being a continuous line of revolution formed by the intersection of two difierently generated curves on one face of the major portion and the top thereof being a transverse cliif type edge having a curved surface of a radius greater than the radius of the continuous line of revolution and intersecting said line at the sides of the seat and being concaved downwardly with respect to the horizontal meridian of the lens, and a minor portion of lens medium of different index of refraction secured to said seat and conforming in outline thereto, the top edge of said minor portion having substantial thickness and the side and bottom edges thereof having substantially no thickness, the said top edge along the vertical meridian of the lens being located adjacent to and below the center of the major portion, the

concavity of the said top edge being such ,as to provide a wide entrant field of vision when the eye passes from one focal field into the other.

MAX A. LAABS. 

